Dear Dr. Richardson,

Thank you for your detailed responses to the reviewer comments. Both reviewers were in favor of publication of your manuscript and consider this a significant contribution to Biogeosciences. Both reviewers, however, had a series if concerns that need to be addressed prior to publication. Your detailed author comments highlighted how you intend to address these concerns. I welcome your revised manuscript with these major revisions as suggested in your author responses.

I would, however, suggest to eliminate the section on the box model as both reviewers voiced significant concerns with this section. I agree with the concerns that in the absence of comprehensive measurements of all deposition and losses, the box model simulations require many assumptions that are difficult to justify.

I am looking forward to seeing your revised manuscript.

Best regards,
Daniel Obrist

Dear Dr. Richardson,

Two experts re-reviewed your manuscript and commented that the revised manuscript addresses all their previous concerns. Therefore, I am glad to accept your manuscript for publication in Biogeosciences. I would like to ask you to implement a few minor edits as suggested by the reviewers in a last manuscript version that will be submitted as a final manuscript for publication.

Thank for your considering Biogeosciences for publication of your work.
Daniel Obrist